Our quarries in the central range have this blasted free, a hard material for use in making cement.It superficially resembles Akadama, but I think it is clay that met the sea salt, at the river's mouth was deposited, pressured and uplifted in the islands past. Probably came from the heights of Venezuela, via the pre- Orinocco river.High in calcium as well.

Jim, probably knows the correct version.

Anyhow, you can get grain sized versions of this earth yellow material. This root of a fukien tea, has been in the mix of 75 to 80 % yellow hard material and the rest as compost, since the beginning of the year, and grows well. Will try on a much larger tree next year.Khaimraj

"Seems to work" is important. Work cautiously; I have had some terrible luck with soils that appeared healthy but were not. Eastern Oregon mines a clay particle for cat litter. Little did I know that it is mined from dry lake beds and had too much salt in it. Your clay might be similar. Calcium affects the pH, but you can test for that with litmus paper or a soil meter. Without a track record for your soil, I would not use it on your favorite trees...........yet. Good luck!Herb Gustafson

Yes great to hear from you Herb. I have a few of your books and found your chapters on soil very informative Finding inorganic substrates here in Australia is often difficult. Just as we find a source the company goes through changes suppliers change sources and we start all over agian. I was lucky enough to notice one of the guys at work using an oil spill soaker that I had not seen before. From experience it looked like the good diatomite that we mine here in the north but finding a supplier can be difficult. Headed to the local tool supply store to get a couple of bags only to find that they too have changed their supplier and there was only one bag of the old stuff my work mate had been using. Good luck KhaimrajTwo substrates we have had good success with down under is crushed brick and terracotta. My local landscape supplies had plenty of the crushed terracotta last year but now that source has dried up too

normally I used the broken brick from the hollow clay block factories. Crushed sifted brick.Otherwise if the factory were to shut down, I would have to shift to a clay we have pre-fired by underground oil deposits that burnt them.Khaimraj